Set the environment variable `VAULT_ENABLE_FILE_PERMISSIONS_CHECK` to have the
Vault process automatically verify that the user running Vault owns and can
access the configuration directory and all related files.

The file permission check also confirms that no other group or user has write or
execute permissions on the configuration directory or files.

You can set explicit users and permissions on the plugin directory and plugin
binaries with the `plugin_file_uid` and `plugin_file_permissions` parameters in
your Vault configuration if the users or permissions need to be different from
the Vault process.

Vault does not verify file permissions by default.